Method of continuous open-pit mining and apparatus therefor



Jan. 31, 1967 J, w. HEIMASTER 3,301,599

METHOD OF CONTINUOUS OPEN-PIT MINING AND APPARATUS THEREFOR 4Sheets-Sheet 1 Filed Feb. 2'7, 1964 INVENTOR JOHN W. HEIMASTER BY KM ATTORNEY Jan. 31, 1967 J. w. HEIMASTER 3,391,599

' METHOD OF CONTINUOUS OPEN-PIT MINING AND APPARATUS THEREFOR 4Sheets-Sheet 2 Filed Feb. 27, 1964 WENEHEH NILE;

WIRE.

W O N w E i TER J H .H IM 5; BY

A TTORNE V Jan. 31, 1967 J. w. HEIMASTER 3,3915% METHOD OF CONTINUOUSOPEN-PIT MINING AND APPARATUS THEREFOR Filed Feb. 27, 1964 4Sheets-Sheet 5 1 INVENTOR.

JOHN W.HElMASTER ATTORNEY Jan. 31, 1967 J. w. HEIMASTER 3,301,599

METHOD OF commuous OPEN-PIT MINING AND APPARATUS THEREFOR Filed Feb. 27,1964 4 Sheets-Sheet 4 ENTOR JOHN W.HE|MASTE ATTORNEY United StatesPatent METHOD OF CONTINUOUS OPEN-PIT MINING AND APPARATUS THEREFOR JohnW. Heimaster, Charleston, W. Va., assignor to Union Carbide Corporation,a corporation of Ne York Filed Feb. 27, 1964, Ser. No. 347,753

7 Claims. (Cl. 29918) This invention relates to a novel method foropen-pit mining. More particularly, this invention relates to a methodfor open-pit mining wherein the strata containing potentially valuableminerals are removed in a substantially continuous manner. In a stillmore particular aspect this invention relates to a method forsubstantially continuously mining coal in an open pit mine.

In many areas of the world coal seams are found fairly near the surface,so that the overburden can be stripped and the uncovered seam mined. Inthe past, mining of these seams generally has been effected bydynamiting the seam and loading the resulting coal fragments with ashovel onto a truck for transportation from. the mine site. Thistechnique is not particularly desirable, however, because, in additionto the dangers inherent in the use of explosives, it is not aparticularly economical method due to its cyclic nature which requiresidle crews and machinery during the blasting operation and the like.

It has been found by this invention that coal and other seams of thistype can be easily, safely and economically mined by continuous miningsystems of the type heretofore employed in underground mines. Thesecontinuous mining systems generally comprise, in combination, amechanical means for disintegrating and dislodging the strata materialfrom the seam and a means for substantially continuously andsimultaneously transporting the disintegrated strata material from thelocus of the disintegration means to a substantially separate place,such as a continuous miner in combination with a conveyor systemextending out of the mine.

The area to be mined is prepared by any convenient technique, i.e., theoverburden is removed from the seam to be mined with shovels,bulldozers, draglines, wheel excavators and the like. After the removalof the overburden the seam is mine-d in accordance with the method ofthis invention.

The mining technique of this invention generally comprises the removalof the selected strata from a plurality of substantially linear,parallel and contiguous troughs or courses of substantially the sameheight and width. Each course being mined has a floor, at least one sidewall and an end formed from the surrounding, in-place strata material,but has no ceiling. In a preferred embodiment of this invention thecourse being mined is laterally displaced from any drop-off by adistance sufficient to provide subadjacent support to the course beingmined.

- Each course is formed by the mechanical disintegration and dislodgingof the selected strata material, for example coal, 'from a "wall whichis transverse the direction of generation of the course; i.e., an end ofthe course. The disintegration and dislodging is accomplished by the useof apparatus such as the continuous miners of the type heretoforeemployed in bore mining, such as rippers, borers and the like.Continuous miners of this type are disclosed in US. Patent No. 1,603,621to McKinlay; U.S. Patent No. 2,695,164 to Arentzen;'U.S. Patent No.2,788,- 200 to Barret-t; U.S. Patent No. 2,699,328 and U.S. Patent No.2,826,402 to Alspaugh et al.; U.S. Patent No. 2,719,709 to Salmons; U.S.Patent No. 2,734,731 to Cartlid-ge et al.; and U.S. Patent No. 2,776,125to Robbins et al. These continuous miners generally comprise aselfpropelled vehicle having mounted on one end thereof means formechanically disintegrating and dislodging the selected strata and meansfor removing the dislodged strata fromthe immediate area being mined. Itis preferred that the continuous miners be employed in combination witha train of conveyors, such as those described in U.S. Patent 2,722,409to Bergmann, U.S. Patent 2,780,451 to Alspaugh et al. and U.S. Patent2,948,552 to Moon. When such a train is employed it is preferred thateach conveyor be self-propelled so that the miner is not required to towthe conveyor train.

The mining method of this invention is illustrated in the accompanyingdrawings in which:

FIGURE 1 is a fragmentary plan view of a coal mine in which the methodof this invention is being carried out;

FIGURE 2 is a fragmentary elevation view, partly in section, taken alongline 22 in FIGURE 1, of a coal mine being mined in accordance with thisinvention;

FIGURE 3 is a fragmentary cross-sectional view, taken along line 33 inFIGURE 1, of a coal mine being mined in accordance with this invention;

FIGURES 4 through 6 illustrate a preferred sequence of steps employed inthe utilization of the mining method of this inveniton;

FIGURE 7 is a fragmentary elevation view, partly in section, of a miningmachine adapted for use in the mining method of this invention;

FIGURE 8 is a cross-sectional view, taken along line 88 in FIGURE 7, ofa mining machine adapted for use in the mining method of thisinvent-ion;

FIGURE 9 is a rear schematic view of a mining machine adapted to cut agroove in the floor of the course being mined to aid in steering theconveyor train employed in combination with the mining machine;

FIGURE 10 is a cross-sectional fragmentary view taken along line 1010 inFIGURE 9;

FIGURE 11 is an elevation view, partly in section, of a suitablesteering mechanism for the conveyor units employed in conducting themining method of this invention; and

FIG. 12 is a plan view, partly in section along line 1212 in FIGURE 11,of the steering mechanism.

With reference mainly to FIGURES 1 through 3, the apparatus employed incarrying out the method of this invention comprises generallyself-propelled continuous miner 1 equipped with disintegrating anddislodging means 3, means for collecting the disintegrated coal, notshown, and means 5 for transporting the disintegrated coal to the rearof mining machine 1. A train of self-propelled conveyors 7 is attachedto the rear of mining machine 1 and extends behind mining machine 1 outof the course being mined and ultimately parallel to belt conveyor 9 anddischarges the coal onto belt conveyor 9 for transportation away fromthe mine site.

In operation, continuous miner 1 is trammed across the surface of coalseam 11, from which the overburden has ben removed, to point 13 adjacentto unremoved overburden 15. The miner then mines a generally downwardlyinclined ramp 17 until the depth of cut 1 9 approximates the height ofdisintegration and dislodging means 3 of miner 1, and then mines asubstantially horizontal linear course A (FIGURES 4 and 5) for the fulllength of the exposed seam. The miner is then trammed back out of thecourse thus mined and to a position adjacent to said course and minescourse B and then, in a similar manner, mines courses C and D. The mineris again trammed out of the pit and back to point 13, down ramp 17 andextends'ramp 17 until the depth of cut again approximates that of theheight of disintegration and dislodging means 3 of miner 1, and minescourse E. The pattern is then continued until the full depth of the seamis reached, for example, with course M in FIGURES 4 and 5, when theminer is riding on the underlying strata 21. In FIGURES 1 through 3, theminer is shown part way through course H. The sequence is continueduntil, with course a in FIG- URE 6, the full width of the exposed seamhas been mined to a depth approximating the height of disintegration anddislodging means 3 of miner 1. The general mining sequence is continueduntil, with course m in FIGURE -6, the full width and height of exposedseam 11 has been mined.

The sequence outlined above and illustrated in FIG- URES 1 through 6 isnot critical, and other sequences can be employed as desired. It ispreferred, however, that the course being mined be separated laterallyfrom dropoff 23 by a distance 25 sufficient to provide sufficientsubadjacent support to the strata on which miner 1 rests to prevent itscollapse clue to the weight of mining machine 1. The magnitude ofdistance 25 will vary depending upon the strength of the seam beingmined as well as the width of the course. In general, however, thisdistance will be equal to at least one-half the width of a singlecourse, and preferably one width of a single course, as is shown in thedrawings.

Modifications of this technique can be readily employed if desired. Forexample, although the technique shown and described results in theproduction of high vertical side walls, it is clear that one can leavestepped walls if desired. Similarly, the ends of the various courses canbe in substantially the same plane, leaving a vertical end extending thefull height and width of the seam being mined or, in the alternative,the courses on the lower levels can be shorter than those immediatelyabove, resulting in a stepped end. Moreover, the courses need not bearranged vertically, as shown in FIGURES 4 and 5, but can be staggeredif desired.

The conveying system employed can be varied as desired. For example,instead of employing a train of conveyors as shown in the drawings anddescribed above, one can employ a stationary conveyor system situated ona shelf above or below the shelf of the course being mined and a minerwhose conveyor is adapted to discharge onto the stationary conveyor.Alternatively, one can direct the discharge from conveying means 5 to apoint behind mining machine 1 or to an adjacent shelf above or below thecourse being mined and collect the disintegrated coal with aself-propelled coal loader of the type known to the art in combinationwith a conveyor train.

The continuous mining machines which are employed in the method of thisinvention fall into two general classes: (1) those whose disintegrationand dislodging' means comprise a plurality of rotary front-face cutters,such as those disclosed in the patents to McKinlay, Salmons, Cartlidgeet al., Robbins et al. and Alspaugh et a1.; and (2) those whosedisintegration and dislodging means travel about an axis which issubstantially parallel to the wall being mined, such as ripper minersand the like as disclosed in the patents to Barrett and Arentzen. Minersof the first class are gene-rally preferred for use in the method ofthis invention because of their ability to continuously generate asubstantially vertical face perpendicular to the direction of travel,whereas the miners of the second class generate the face in a cyclicmanner by sweeping vertically up and down the face and horizontallyacross the face.

Because all the continuous miners vigorously agitate the coal as it isdisintegrated and dislodged, it is necessary to provide the miner withmeans for confining the dislodged coal to the proximity of the facebeing generated by the machine. This is readily accomplished byproviding the mining machine with a shield extending from behind thedisintegration and dislodging means forward to the face being generatedin seam or, if desired, beyond the face and overlapping the face.

One suitable shield arrangement is shown schematically in FIGURES 7 and8. The shielding comprises generally ver ical .rfi shield .27 .afiixedto mining machine 1 at a point behind disintegration means 3, shown inphantom, normally horizontal rotatable shield '29 and removable sideshield 31. Rear shield 27 is of such configuration and projected area asto approximate the configuration and projected area of face 33 beinggene-rated by disintegration and dislodging means 3 in seam 11. Normallyhorizontal shield 29 lies in a generally horizontal plane above thelevel of the top of disintegrating and dislodging means 3 and is ofsuificient width and depth to extend from rear shield 27 forwardlybeyond face 33 and a suffi-cient distance to either side ofdisintegration and dislodging means 3 to overlap wall 35 in the coursebeing mined and wall 37 of the adjacent course. Horizontal shield 29 isrotatably mounted on support arm 39 and mast 41 to rotate about axis 43,and is supported in a normally horizontal position by flexible cable orchain 45 running from the top of mast 41 to projection 47 in horizontalshield 29. Thu-s, shield 29 may rotate upwardly to clear the ground inthe event mining machine 1 makes too deep a cut but is restrained fromcontacting disintegrating and dislodging means 3. Side shield 31 isremovably mounted on rear shield 27 and is of sufiicient height toextend from about the surface of the seam on which mining machine 1rides to above the plane of horizontal shield 29 a distance sufficientto provide a seal in the event shield 29 is rotated upwardly. Sideshield 31 also extends from rear shield 27 forwardly beyond face 33 inseam 11 in a substantially parallel relationship to wall 37 of theadjacent course. Side shield 31 is rem-ovalbly mounted to permit the useof mining machine 1 in the generation of the first course of any levelin the mine. The bottom edge of side shield 31 is bevelled at 49 toprovide clearance in the event the cutter head of mining machine 1 is ona downward tilt with respect to the surrounding strata.

Various modifications of the shielding will readily occur to thoseskilled in the art. For example, side shield 31 may be removablyattached to horizontal shield 29, instead of rear shield 27, the machinemay be adapted to permit the use of side shields on either or both sidesand the like.

To aid in controlling the conveyor train during the mining operation,particularly during t ramming, it is preferred that mining machine 1 beequipped with a cutter bar oriented to cut a. groove in the floor underthe mining machine and that the wheels of each conveyor be steerable inresponse to the movement of a guide wheel riding in the groove.

A suitable arrangement for mounting the cutter bar is shown in FIGURES 9and 10 and for the conveyor steering system is shown in FIGURES l1 and12.

With reference to FIGURES 9 and 10, a conventional cutter bar 51containing chain 53 and cutting elements 55, of sufiicient length to cutshallow groove 57 in the floor of scam 11 is mounted on arm 50 attachedto the rear of machine 1. Chain 53 and cutting elements 55 are driven inthe direction of arrow 61 by flange-mounted gear motor 63 which is alsomounted on arm 59. Because most mining machines pivot about a pointforward of the rear of machine 1, arm 59 is preferably mounted on slide65 riding in guides 67 attached to the rear of machine 1. Arm 59 isurged sideways by single-acting hydraulic cylinders 69 and pistons 71 tomaintain the cutter bar approximately on the center line of the coursetaken by machine 1 and to prevent the generation of too wide an arc ingroove 57 on turning. Cutter bar 51 is raised and lowered bydouble-acting hydraulic cylinders each mounted on axle 81 secured toupstanding pivot 83 attached to the bottom of conveyor unit 85. Forturning each axle 81 about pivot 83 lever arm 87 forms a bell crank withaxle 81. The outer ends of lever arms 87 are connected by common link 89which is pivotably connected at 91 to groove follower support member 93horizontally rotatable about vertical pivot 95 under unit 85. Member 93carries groove following means, such as spaced rollers 97 projectingdownwardly into groove 59 in seam 11. Rollers 97 are equally spaced frompivot 95 a distance great enough to give the desired mechanicaladvantage for easy steering. Groove follower support member 93, whenangularly displaced -by groove 57, swings connecting link 89 toward onewheel 79 or the other, causing both wheels to be turned in the desireddirection. Tension spring 99 is connected between projection 101depending from the bottom of unit 85 and the end of member 93 fornormally urging the steering mechanism in a centralized position.

Convey-or unit 85 is connected to conveyor unit 103 by swivel tongue 105projecting between bifurcated lug 107 into which coupling pin 109 isurged by compression spring 111 extending around pin 109.

What is claimed is:

1. Method for mining a selected geological strata material from whichthe overlying strata have been removed which comprises substantiallycontinuously generating a generally downwardly inclined course from thesurface of said strata material to a desired depth and thereaftersubstantially continuously generating a substantially horizontal courseas an extension of said inclined course through said strata material,generating a second course contiguous to and substantially parallel withthe first course and repeating the sequence until the width of theexposed strata material has been traversed, each course having a floor,at least one side, an end and no ceiling, each course being generated bysubstantially continuously disintegrating and dislodging the stratamaterial from said end, and substantially continuously andsimultaneously removing the dislodged strata material from the end ofsaid course and transporting it to a substantially separate place.

2. Method for mining a selected geological strata material from whichthe overlying strata have been removed which comprises substantiallycontinuously generating a generally downwardly inclined course from thesurface of said strata material to a desired depth and thereaftersubstantially continuously generating a substantially horizontal courseas an extension of said inclined course through said strata material,generating a second course contiguous to and substantially parallel withthe first course and repeating the sequence until the width of theexposed strata material has been traversed, each course having a floor,at least one side, an end and no ceiling, each course being generated bysubstantially continuously disintegrating and dislodging the stratamaterial from said end, confining the dislodged strata material to azone adjacent to said end, and substantially continuously andsimultaneously removing said dislodged strata material from said zoneand transporting it to a separate place.

3. Method for mining a selected geological strata material from whichthe overlying strata have been removed which comprises substantiallycontinuously generating a generally downwardly inclined course from thesurface of said strata material to a desired depth and thereaftersubstantially continuously generating a substantially horizontal courseas an extension of said inclined course through said strata material,generating a second course parallel to and contiguous with the firstcourse and thereafter generating in a similar manner a sufiicient numberof courses to traverse the exposed width and depth of said stratamaterial, each course being generated having a floor, at least one side,an end and no ceiling and being laterally separated from a drop-off by adistance sufficient to provide subadjacent support to said course, eachcourse being generated by substantially continuously disintegrating anddislodging the strata material from said end, and substantiallycontinuously and simultaneously removing the dislodged strata materialfrom the end of said course and transporting it to a substantiallyseparate place.

4. Method for mining a selected geological strata material from whichthe overlying strata have been removed which comprises substantiallycontinuously generating a generally downwardly inclined course from thesurface of said strata material to a desired depth and thereaftersubstantially continuously generating a substantially horizontal courseas an extension of said inclined course through said strata material,generating a second course parallel to and contiguous with the firstcourse and thereafter generating in a similar manner a sufficient numberof courses to traverse the exposed width and depth of said stratamaterial, each course being generated having a floor, at least one side,an end and no ceiling and being laterally separated from a drop-off by adistance sufficient to provide subadjacent support to said course, eachcourse being generated by substantially continuously disintegrating anddislodging the strata material from said end, confining the dislodgedstrata material to a zone adjacent to said end, and substantiallycontinuously and simultaneously removing said dislodged strata materialfrom said zone and transporting it to a separate place.

5. A continuous mining machine comprising in combination aself-propelled vehicle having mounted on one end thereof means fordisintegrating and dislodging selected strata material from a solid seamof said material and means for confining the disintegrated and dislodgedstrata material to the proximity of the disintegration and dislodgingmeans comprising (1) a generally vertical shield behind saiddisintegration and dislodging means having a projected area andconfiguration which approximates the projected area and configuration ofthe face generated by said disintegnation and dislodging means; (2) anormally horizontal shield located in a generally horizontal plane abovesaid disintegration and dislodging means and extending from saidvertical shield forward to and beyond the plane of the face generated bysaid disintegration and dislodging means and extended laterally adistance equal to at least the width of the face generated by saiddisintegration and dislodging means, said horizontal shield beingrotatably mounted on an axis behind said dis-integration and dislodgingmeans; and (3) at least one removable, substantially vertical sideshield extending from said vertical shield forward to and beyond saidface and from the level on which the machine rides upwardly at least tothe plane of said horizontal shield.

6. The mining machine as claimed in claim 5 wherein said side shield isremovably attached to said horizontal shield.

7. The mining machine as claimed in claim 5 wherein said side shield isremovably attached to said vehicle and extends upwardly to a heightwhich is greater than the normally horizontal plane of said horizontalshield.

References Cited by the Examiner UNITED STATES PATENTS 2,920,879 l/19-60 Driehaus 299-64 3,098,641 7/1963 Baldwin 299-18 X 3,169,797 2/1965Lundquist 299-64 3,190,696 6/1965 Stalker 299-18 X ERNEST R. PURSER,Primary Examiner.

1. METHOD FOR MINING A SELECTED GEOLOGICAL STRATA MATERIAL FROM WHICHTHE OVERLYING STRATA HAVE BEEN REMOVED WHICH COMPRISES SUBSTANTIALLYCONTINUOUSLY GENERATING A GENERALLY DOWNWARDLY INCLINED COURSE FROM THESURFACE OF SAID STRATA MATERIAL TO A DESIRED DEPTH AND THEREAFTER,SUBSTANTIALLY CONTINUOUSLY GENERATING A SUBSTANTIALLY HORIZONTAL COURSEAS AN EXTENSION OF SAID INCLINED COURSE THROUGH SAID STRATA MATERIAL,GENERATING A SECOND COURSE CONTIGUOUS TO AND SUBSTANTIALLY PARALLEL WITHTHE FIRST COURSE AND REPEATING THE SEQUENCE UNTIL THE WIDTH OF THEEXPOSED STRATA MATERIAL HAS BEEN TRAVERSED, EACH COURSE HAVING A FLOOR,AT LEAST ONE SIDE, AN END AND NO CEILING, EACH COURSE BEING GENERATED BYSUBSTANTIALLY CONTINUOUSLY DISINTEGRATING AND DISLODGING THE STRATAMATERIAL FROM SAID END, AND SUBSTANTIALLY CONTINUOUSLY ANDSIMULTANEOUSLY REMOVING THE DISLODGED STRATA MATERIAL FROM THE END OFSAID COURSE AND TRANSPORTING IT TO A SUBSTANTIALLY SEPARATE PLACE.